update mappings documentation pages for greater signal:noise

[turbomam]

don't show self and native mappings unless they show novel information. If the schema's default prefix is 'nmdc' and the element's name is 'tiger', we don't need to see two additional lines of 'nmdc:tiger'

mappings that are not broad, narrow, exact, etc should not be reported as beign of the "type" 'undefined". either use a word like "unqualified" or "mappings" or just leave the type blank. (@sujaypatil96 and I have talked about addressing that in SchemaView())

"mappings" is probably the best choice since it doesn't unilaterally add a new word to this universe

[turbomam]

see also

• update mappings documentation pages for greater signal:noise #2289
• Render Mappings section generally on all element documentation pages #2087